Estimation of the stress state from stress-induced failures and data from drill core

Purpose and goal
The aims of this pre-study are to: 1. Constrain the state of stress from stress-induced failure (SIF) and drill core data from 1.0–1.8 km depth in the LKAB mine in Malmberget. Problems in operation for traditional methods start to occur at these depths. The results will be validated against other stress measurement methods. 2. Consider the influence of structures and geochemistry for the estimation of the stress magnitudes. 3. If possible, prepare for a full-scale innovation or pilot project on constraining the state of stress in using SIFs and drill core data.

Structure and implementation
The study will be conducted by C. Wanhainen, D. Ask, M. Ask and T. Bauer. It has five activities: 1. Literature study. 2. Data analyses of existing data and complementary testing. Analysis of selected SIFs and evaluation of stress magnitudes from rock mechanics, structural geology and geochemistry data. If possible, do complementary testing. 3. Constrain stress magnitudes and validate results against hydraulic stress data. 4. Dialogue with preliminary LKAB. 5. Submit results for publication and develop a work plan for a full-scale innovation project.

Expected results
The plan is to test and develop a new, cost-effective method for constraining the state of stress at greater depths, and to validate the results against the “answer” (i.e. hydraulic injection data). This will lead to improved safety, and provide critical data for the design of deeper level mining.If the outcome is according to plan, we anticipate developing a full-scale innovation or pilot project in order to apply the results from this study in other parts of the Malmberget mine and in the Kiruna mine.